Trouble falling asleep or staying asleep plagues one in three American adults. Insomnia can occur in people of all ages, usually just for a night or two, but sometimes for weeks, months or even years.

What are Some Types of Insomnia?
Transient Insomnia:
Transient Insomnia is the inability to sleep well over a perios of a few nights, but lasts less than four weeks. This type of insomnia is usually brought on by excitement or stress.

Short-term Insomnia:
Periods of ongoing stress at work or at home can result in four weeks to six months of poor sleep. When the stressful situation eases up or when the sleeper adjusts to it, sleep will usually return to normal.

Chronic Insomnia:
More than 20 million Americans complain of Chronic Insomnia - poor sleep every night or most nights for more than six months. According to a nationwide study by the Association of Sleep Disorders Centers, physical ailments such as disorders of breathing or muscle activity are often mistaken for insomnia and may account for a large number of self-diagnosed cases of insomnia.

What are Some Types of Insomnia?

Learned Insomnia (also known as Primary Insomnia):
If you sleep poorly during times of stress, you may worry about not being able to function well during the day. You may decide to try harder to sleep at night but, unfortunately, this determined effort can make you more alert and set off a new round of worried thoughts, causing sleep loss.

What is Secondary Insomnia?
When insomnia is caused by a psychiatric disorder (most often depression) or a medical disorder (most often chronic pain) it is termed Secondary Insomnia. Secondary Insomnia may be relieved by successful treatment of the primary psychiatric/medical disorder.

More info:

Sleep Hygiene information from the National Sleep Foundation

The Complete Guide to Managing Insomnia